The present invention relates to methods of and apparatuses for epitaxially growing a chemical-compound crystal, in which a plurality of raw-material gasses are alternately introduced into a closed chamber of a crystal growing device to grow the crystal and, more particularly, to a method of and an apparatus for epitaxially growing a chemical-compound crystal, in which a growing rate of a growing film of the chemical-compound crystal is controlled at growing of the crystal.
In an epitaxial growing method for a chemical-compound crystal, it is very important to control a growing rate of a growing film of the crystal at growing of the crystal. Conventionally, in a molecular-beam epitaxial growing method and a migration enhanced epitaxial growing method, vibration of a reflection high-energy electron diffraction (hereinafter referred to as "RHEED") is utilized to control the growing rate of the growing film of the order of a monomolecular layer. This is reported in the paper, Jpn. J. Appl. Phys. Vol 23, No. 9 PPL 657-L659 (1984); T. Sakamoto, et al., for example.
In practice, the crystal is grown while rotating a crystal substrate, in order to secure uniformity in a plane of the crystal film.
In the case where the crystal is grown while rotating the crystal substrate as described above, a direction of a crystal axis and a direction of the high-energy electron beam change due to the rotation of the crystal substrate. Thus, it is practically impossible to control the thickness of the growing film of the crystal by the RHEED.
In the existing circumstances, accordingly, the thickness of the growing film of the crystal is controlled by the same conditions as growing conditions which are obtained when the crystal substrate is fixed against rotation. For this reason, it is required to regulate or control charge amounts of the respective raw-material gasses into the crystal growing device by crucibles or the like which are controlled in temperature extremely precisely.
Further, there is the following problems. That is, influence of emission of the high-energy electron beam to the surface of the growing film gives rise to defects in the crystal. Because of the use of the electron beam, the interior of the crystal growing device must be maintained at super high vacuum.